Liquid heater



Oct. 4, 1938. c. K. BENNETT 7 LIQUID HEATER Filed Jan. 14; 1937 3 Sheets-Sheet l Oct. 4, 1938. c. K. BENNETT LIQUID HEATER Filed Jan. 14, 1937 3 Sheets-Sheet 2 //VJ E/V70/F c /mm igpmgza Oct. 4, 1938. c. K. BENNETT 2,132,093

LIQUID HEATER I Filed Jan. 14, 1937 is SheetS Shee t s WIT/V558. 60

Patented 4, 193a PATENT o FlcE noun) HEATER Clement K. Bennett, Philadelphia, Pa., assignor I to C. H. -Wheeler Manufacturing Company, Philadelphia, Pa, a corporation of Pennsyl vania Application January 14, 1937, serial Nc. 120.533

' 8 Claims. .o 251-225) This invention relates to a liquid heater and particularly to a water heater to which steam is I applied during the blow down of wood fiber digesters.

In normal operation digesters are operated at about 100 lbs. per square inch pressure and are arranged to cook wood fiber for extended .periods of time, normally around two or more hours. At the end of the cooking period the pressure is reduced to about 75 lbs. per square inch and the blowing takes place at such pressure. The contents of the digester during'the blowing operation are discharged into a tank having approximately one and one-half times the capacity of the digester, the blowing taking from eight to fifteen minutes time. In general the blow'down may occur approximately every six hours from a single digester.

From the blow down tank the steam which is formed is generally passed through a separator into a blow down heater wherein the latent heat content is recovered and used for heating process water or other liquid. s

It sometimes happens that operators are careless about the liquid level in the blow tank or in the manner of blowing and the liquid level may then reach too high a level in the blow tank, in which case liquor is blown over into the heater. When this occurs the paper pulp contained in theliquor quickly foulsand plugs the heat exchange surfaces and the efliciency of the heater is very much reduced. Even if the liquor is not blown over due to too high a liquor level, the flashing of water into steam takes place almost explosively and the repidity of flow causes a carrying over into the heater of very considerable quantities of the wood fiber which will be de-' posited upon the heat exchange surfaces of the heater.

As a result of ."the fouling which thus occurs ample provision must be made in properly designed blow down heaters to permit periodic sions being made for free expansion and contraction of the tubes which it contains.

Heretofore it has been generally customary to use substantially an ordinary surface condenser as a blow down heater with some additional provision for the insertion of a hose to wash on the tubes. The arrangement of tubes in the conventional surface condenser is by no means 's'atisfactory in such cases since in general it is found that while high pressure water may remove the wood fiber from the tubes nearest its inlet, it may serve to compact the wood fiber even more into remoter locations. Furthermore, the conventional surface condenser must be specially made to provide for uneven expansion'necessitated by the very rapid impingement of steam upon cold surfaces. which is being heated are also generally arranged in a fashion which contributes in'causing asymmetrical stresses to be set up in the heater. 'It is a general object of the present invention to provide an improved'liquid heater (generally for heating water) designed for use in conjunction with the blowing down of wood fiber digesters. In the attainment of this object provision is made first for the reduction of the strains incidental to the very rapid heating of a cold apparatus by insuring that the heating takes place in a symmetrical fashion with respect to the mechanical structure. This is accomplished by providingradial symmetry for the multiple liquid passes together with a single passage of the steam in such fashion that substantially all of Ythesteam is caused to first impinge upon the out the imposition of :gre'at strains upon, the,

structure.

Secondly, provision is made for the complete and easily accomplished cleaning of the surfaces of the tubes. This end is accom'plished by reason of the radial symmetry of the arrangement in conjunction with the provision of suitable passages for high pressure liquid introduced from the outside of the shell and also by the strategic location of wash down nozzles for causing washing water to flow downwardly along the vertical tubes in such fashion as to reach Other objects of the invention relate primarily to details of 'construction'which will be apparent from the accompanying drawings in which Figure 1 is an elevation of a heater constructed in accordance with the invention. certain parts be-.

The multiple passes of the cold water v and wash all of them.

ing broken away and shown in section to clarify the internal construction. I

Figure 2 is a section taken as indicated at 2-2 inFigure 1; Y

Figure 3 is a plan view or the heater showing the manifolding of the wash down nozzles; Figure 4 is a vertical section showing the arrangement and construction of a wash down nozzle;

Figure 5 is a fragmentary vertical section taken on the plane indicated at 55 in Figure 1; and

Figure 6 is a fragmentary section showing specifically the mode of connecting the floating tube plate and its cover.

The heater comprises a shell 2 extended at its lower end, as indicated at 4, into a non-condensible gas belt 6 provided witha gas outlet 1. The provision of the skirt provided by the extension 4 prevents to a considerable extent the carrying out with non-condensible gases of steam condensate. The lower wall of the belt 6 may be made square so asto provide corners extending beyond the circular portions of the apparatus to provide feet on which the apparatus may be supported.

A lower outside shell cover In is provided having a condensate outlet l2. This is secured to the underfide of the plate 8.

The upper end of the shell 2 is continued as indicated at I4 and IS. The first continuation ll opposite this steam inlet and causes the steam provides a steam impingement baille cut away at its lower corners, as indicated at Hi, to permit the reaching of the tubes by the stream from a washing nozzle. Surrounding the upper end of the shell and extending somewhat below the extension II is an, eccentric belt l8 provided at its point of maximum diversion from the shell with a steam inlet indicated at 20. The baflie ll is to flow laterally within the eccentric belt it so that it is distributed substantiallyuniformly to the periphery of the tube bundle. The belt II is provided with a bottom plate 22 shaped to .fill the space between the outer wall of-the belt and the shell 2. Drain openings 24 are provided in this plate 22, these openings being normally covered by suitable cover plates bolted thereto.

The top 20 of the belt It serves to support the fixed tube plate 20, which in turn is surmountedby the water distributing head 20. This head is provided with a water inlet passage 32 feeding water into a central pass of tubes, an annular connecting passage 24 and an outer annular water discharge passage 38. The construction shown is designed to provide four water passes, the water or other liquid being led first to the innermost pass and then successively through the intermediate passes to the outermost one, from which it is discharged into the passage 26. The symmetrical arrangement of the successive passes is indik cated in Figure 2. The tube bundle at its lower end-supports the floating tube plate ".which is provided with a cover 42 containing suitable partitioning means to provide connections between the first and second and the third and fourth passes, as indicated at 48 and 50. A central opening 46, through the cover, is aligned with a central opening 44 through the tube plate 40 to provide for the passage of condensate into the cover l0.

The connection between the floating cover 42 and the tube plate 40 is worthy of note and is indicated onan enlarged scalein Figure 6. The connection is made by means ofa series of hook bolts generally indicated at 52 and comprisini upper hook ends it forwarded integral with bol extensions 52 threaded to receive nuts 60. The heads 58 are provided with hook elements 6! designed to be received in an annular groove 62 formed adjacent the periphery of the upp r surto prevent blowout. Besides the connection by means of the hook bolts, there are providedstay bolts between the cover 42 and tube plate 40.

. Nozzles 66 'are provided inproper locations rel- .ative to the tubes to introduce the necessary 'water for washing down-the outside of the tubes.

These nozzles 66 are shown in Figure 4 and comprise vertically extending pipes carrying distribution nozzles 68. Each of the pipes is threaded into a coupling I0 secured by a member 12 to the upper end of a tube 14 welded to the cover 30 and drawn down by means of stay bolts 18 in contact with the upper fixed tube sheet 28 with the interposition of suitable gaskets such as indicated at I6 to prevent leakage. Distribution, of wash water to the nozzles is provided through a manifolding arrangement. indicated at 8, receiving the water from a common inlet 82. The pipes of this manifolding arrangement are graduated, as indicated in Figure 3, to insure that all the nozzles receive an adequate supply of water under pressure to insure proper cleaning of all of the tubes. It will be noted from Figure 2 that the tubes 38 are so arranged as to provide a series of eight radial passages which are substantially clear into the innermost pass of tubes throughout the entire vertical extent of the heater. Opposite j these passages there are provided openings 84 normally closed by covers 86 against which press adjustable screws 88 threaded into levers 90 pivoted at 92 and arranged to be held in their closing positions by means of loop members 94.

The covering arrangement just described is readily opened and closed by manipulation of the loop members 84 and screws 88. Through the openings 84 there may be manipulated high pressure water streams for'the purpose of reaching and cleaning the tubes when the accumulation takes place to such extent that the nozzles at the uppermost portion of the apparatus may be inefi'ective to provide complete cleaning. The passages, it will be noted, have between them only relatively small numbers of the tubes, with the result that streams of washing water introduced into any passage will readily effect the washing out into an adjacent passage of accumulated fiber. However, the nozzles 66 are primarily depended upon for washing down purposes. These nozzles are located within the groups of tubesbetween the passages and serve to wash out the accumulated material into the passages. whence it will flow down and out theonenin 44.

A considerable accumulation of fiber and other sediment will occur in the channel formed be tween the extension ll of the shell 2 and the outer wall of the belt 18. Such accumulation may be readily washed out through the openings each other throughout the lengths of the be applicable to single mother multiple pass arrangements, suitable changes being made in the headers to secure the proper flow.

The fact that the cold liquid enters the center and flows to the outside through the successive passes and that the passes are arranged annularly around the center insures a symmetrical distribution of stresses when expansion and contraction take place to prevent any tendency toward lateral buckling of the structure. The symmetry of the stresses is also promoted by the distribution of the steam in the eccentric belt II, which, together with the baille ll, produces a flow oi the steam so as to substantially equally distribute it to all of the outer tubes of the last liquid pass. It will be noted that a counterflow arrangement is substantially provided to further minimize the stresses and promote efliciency.

While an arrangement having a steam inlet at.

the top has been specifically described and is preferable because there is no counterflow of condensate and steam, it is also feasible to cause the steam to enter at the bottom and flow upwardly. In both cases condensate will run down the tubes and aid to some extent in preventing the deposition of flber or other sediment.

It may be remembered that the steam carries over with it both volatile and non-volatile ma-' 4 tween groupsci tubes to provide a multiple pass arrangement providing at least three passes, the groups of. tubes forming the successive passes-being circularly and concentrically arranged, the gas spaces about the various groups being in free communication with each other throughout the lengths of the tubes.

2. A heat exchange apparatus comprising an outer shell,'a passage for the introduction of gas into the shell, a series of tubes extending'longitudinally within the shell, and connections between groups oi. tubes to provide a multiple pass arrangement providing at least three passes, the groups of tubes forming the successive passes being circularly and concentrically arranged with the final pass outermost, the gas spaces about the various groups being in tree communication with each other throughout the lengths oi the tubes.

3. A heat exchange apparatlm comprising an outer shell, a passage for the introduction of gas into the shell, a series of tubes extending longitudinally within the shell, connections between groups of tubes to provide a multiple pass-arrangement providing at least three passes, the groups of tubes forming the successive passes being circularly and concentrically arranged and means for distributing the introduced gas mainly to the outermost group, the gas spaces about the various groups being in free communication with 4. A heat exchange apparatus comprising an outer shell, a passage for the introduction of gas into the shell, a series of tubes extending longi tudinally within the shell, and connections between groupsof tubes to provide a multiple pass arrangement, the groups 0! tubes iorming the passes being concentrically arranged longitu dinally within the shell, said tubes being arranged in groups with passages between the groups, and washing nomles arranged to direct liquid along the tubes within the groups to wash material therefrom into said passages.

5. A heat exchange apparatus comprising an outer shell, a passage for the introduction of gas.

into the shell, a series of tubes extending vertically within the shell, and connections between groups oi tubes to provide a multiple pass arrangement, the groups of tubes forming the passes being concentrically arranged vertically within the shell, said tubes being arranged in groups with vertically clear passages between the groups, and washing nozzles arranged to direct liquid downwardly within the groups to wash material therefrom into said passages. i

6. A heat exchange apparatus comprising an outer shell, a passage for the introduction of gas into the shell, a series of tubes extending longitudinally within the shell, and connections between groups of tubes to provide a multiple pass arrangement, the groups of tubes forming the passes being concentrically arranged longitudinally within the shell, said tubes being arranged in groups with radial passages between the groups, and openings in said shell aligned with the passages for the, introduction of washing liquid to force accumulated material from the tubes into said passages. I

7. A heat exchange apparatus comprising an outer shell, a passage for the introduction of gas into the shell, a series of tubes extending longitudinally within the shell, and connections between groups of tubes to provide a multiple pass arrangement, the groups of tubes forming the passes being concentrically arranged vertically' within the shell, said tubes being arranged in groups with vertically clear radial passages between the groups, and openings in said shell aligned with the passages for the introduction of washing liquid to force accumulated material from the tubes into said passages.

8. A heat exchange apparatus comprising an outer shell, a. passage for the introduction of gas into the shell, a series of tubes extending longitudinally within the shell, and connections between groups of tubes to provide a multiple pass arrangement, said connections including means joining the lower ends of the tubes provided with 9. central wash-out port, the groups of tubes forming the passes being concentrically arranged vertically within the shell, said tubes being arranged in groups with vertically clear radial passages between the groups of the outer passes, and

' openings in said shell aligned with the passages for the introduction .of washing liquid to force accumulated material from the tubes into said passages, the group of tubes forming the'innermost pass surrounding a vertical space, clear of tubes, aligned with said wash-out port.

CLEMENT K. BENNETT. 

